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   Re: [xml-dev] The subsetting has begun

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Mike Champion wrote:
> [hating myself for jumping into this permathread once again :-) ]
> On Fri, 21 Feb 2003 07:16:37 -0500, Elliotte Rusty Harold 
> <elharo@metalab.unc.edu> wrote:
>> Sun's recently posted an alpha of J2ME Web Services 
>> <http://jcp.org/aboutJava/communityprocess/review/jsr172/index.html> 
>> This spec defines a subset of JAXP, SAX, and XML which is only 
>> suitable for processing SOAP messages. ... Among other sins
> Anyone following sml-dev three years ago would not be surprised to hear 
> that vendors are subsetting XML for mobile, data-oriented applications.  
> Where's the "sin" here?  What's a cellphone supposed to do with an 
> external entity reference, or a notation declaration?  Should well-known 
> interoperability antipatterns such as default attribute values be 
> encouraged in lightweight applications?
>> I did not recognize any of the names in the expert group. It is not 
>> clear if there is any real XML expert in the group who actually 
>> understands XML at a deep level.

> Hmm, a group of people out there in the real world took a look at XML, 
> picked what they thought they could use in their target environment, and 
> ignored the rest.  Reminds me of that effort at the W3C in the mid-90's 
> to develop something called "SGML for the Web."

There are two issues that I can see with specifying more dirty than 
quick XML subsets.

First, is that processors targeted to a subset get built, but are 
named after the superset. Now, if someone wants to develop a SOAP 
processor, they should go right ahead. What they should not do is 
call it an XML processor - that muddies the waters. When they do, I 
think we have every right to call foul. For example, over on 
axis-user, I discovered thanks to Denis Sosnoski that XPP3 and 
Electric XML don't process XML as per the spec. It's already been 
discussed here that System.Xml defaults to a subset, and although 
you can configure it to stop acting as System.SOAP and process XML, 
I'm not sure about the other two (Denis says XPP3 can work with XML 
with a parser swapout).

Second, XML is being subsetted for problem domains without much 
visible thought for the cost of that subsetting. How are all these 
optimized systems supposed to work together a few years out? There 
are people who do not appreciate the value of what uniform format 
offers, or what its potential economic value is. Perhaps this is 
because we technologists are mentally stuck on foolish optimizations 
in specification designs as well as software - we're still worrying 
about the metal. Someone on axis-user said that making processors 
comply with the more esoteric parts of XML would be compliance for 
its own sake. But isn't compliance the point? If SOAP ever gets 
subsetted, it will interesting to see how the web services community 

Subsetting XML seems as much an issue for 'interoperability' as 
targeting schemas and infosets does. It's good news that people like 
Don Box and Tim Ewald say they are now appreciating the value of 
staying near XML syntax, but we might be some time waiting for 
consensus that a finger food approach to XML was not such a good idea.

The people behind sml-dev got this right, technically and 
economically - they specified the subset for everyone's use. Perhaps 
similar work could be chartered by the W3C, or kicked off again on 

Bill de hÓra


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